The entrance for Success Academy and Opportunity Charter schools, both of which share space inside Harlem’s PS 241.AP

By unilaterally reversing co-location for several charter schools, including one that has existed since 2008, Mayor de Blasio just snatched the building blocks of upward social mobility from the hands of underprivileged children.

Co-located charter schools must share rent-free space with non-charter public schools, in part because charters receive significantly less operating funds per student and zero funds for bricks and mortar.

Alternative schools like charters and parochial schools can succeed where traditional public schools fail, and they deserve our support. But de Blasio is attacking them.

The situation is dire. Citywide, just 30 percent of students are proficient in math, and 26 percent are proficient in language arts. (It’s even worse upstate. In Buffalo, just 11 percent of third-to-eighth-graders are proficient in language arts and math. In Syracuse, only 7.5 percent are proficient, and in Rochester, just 5 percent.)

Compare those numbers with these: In the Success Charter Network, the city’s largest network of public schools, 82 percent of students are proficient in math, and 58 percent are proficient in language arts. All three schools whose co-location were confiscated are in the Success Charter Network.

It’s no secret that New York City’s teachers unions despise the Success Charter Network and its leader Eva Moskowitz, precisely because Moskowitz has created a system of educating children that works better than New York’s system of failing public schools, and has done so without unionized teachers, thereby demonstrating the huge burden that a union contract puts on public schools.

The incontestable success of charter schools makes de Blasio’s open opposition to them outrageous. In the tale of two school systems, one works and one doesn’t. And Bill de Blasio is siding with the ones that don’t.

For de Blasio, education in New York City isn’t a means of providing children with the skills and background they need to succeed — it’s a means of providing de Blasio with the political coalition that he needs to succeed. De Blasio’s betrayal of New York’s youth cements his support from teachers unions.

In a similar vein, de Blasio’s persistent shill for a tax hike to cover the cost of universal pre-K cements his support from the liberal base of the Democratic Party, who cannot resist a pied piper armed with a “tax the rich!” siren song.

Of course, both State Education Commissioner John King and a Citizens Budget Commission report have warned that universal pre-K in New York City will cost three times what de Blasio is asking for.

The mayor’s education policies are primitive in their support of failing inner-city schools and destructive of superior charter schools, which give choice and hope to ­inner-city families.

The success of many alternative schools can be attributed to a number of factors, including school discipline, innovative curriculums, longer school hours and years and freedom from bureaucratic regulations and union contracts.

I speak from my experience as a founder and former chair of both SUNY’s Charter School Committee and the Student Sponsor Partners organization, which sponsors inner-city high-school students for admission into parochial schools. Our SSP program scrupulously selects average inner-city students for sponsorship, and every year they graduate from their parochial high schools at more than double the rate of inner-city public schools — and for less than half the cost per student.

Studies of the program have proven that the problem with underachieving inner-city students isn’t the student — it’s the system. Charter schools offer high-performing alternatives for parents without the expense of parochial-school tuition.

Educating underprivileged children is the great civil rights issue of our time, and our alternative schools prove that education can be the great equalizer for inner city youths.

But de Blasio’s politically motivated anti-charter bias protects the status quo of special interests and undermines the American promise of equal opportunity for all.